## This file is part of the 'stringi' package for R.
## Copyright (c) 2013-2017, Marek Gagolewski and other contributors.
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#' @title
#' Compare Strings with or without Collation
#'
#' @description
#' These functions may be used to determine if two strings
#' are equal, canonically equivalent (this is performed in a much more clever
#' fashion than when testing for equality),
#' or to check whether they appear in
#' a specific lexicographic order.
#'
#'
#' @details
#' All the functions listed here are vectorized over \code{e1} and \code{e2}.
#'
#' \code{stri_cmp_eq} tests whether two corresponding strings
#' consist of exactly the same code points, while \code{stri_cmp_neq} allow
#' to check whether there is any difference between them. These are
#' locale-independent operations: for natural language text processing,
#' in which the notion of canonical equivalence is more valid, this might
#' not be exactly what you are looking for, see Examples.
#' Please note that \pkg{stringi} always silently removes UTF-8
#' BOMs from input strings, so e.g. \code{stri_cmp_eq} does not take
#' BOMs into account while comparing strings.
#'
#' On the other hand, \code{stri_cmp_equiv} tests for
#' canonical equivalence of two strings and is locale-dependent.
#' Additionally, the \pkg{ICU}'s Collator may be tuned up so that
#' e.g. the comparison is case-insensitive.
#' To test whether two strings are not canonically equivalent,
#' call \code{stri_cmp_nequiv}.
#'
#' What is more,  \code{stri_cmp_le} tests whether
#' the elements in the first vector are less than or equal to
#' the corresponding elements in the second vector,
#' \code{stri_cmp_ge} tests whether they are greater or equal,
#' \code{stri_cmp_lt} if less, and \code{stri_cmp_gt} if greater,
#' see also e.g. \code{\link{\%s<\%}}.
#'
#' Finally, \code{stri_compare} is an alias to \code{stri_cmp}. They both
#' perform exactly the same locale-dependent operation.
#' Both functions provide a C library's \code{strcmp()} look-and-feel,
#' see Value for details.
#'
#'
#' For more information on \pkg{ICU}'s Collator and how to tune it up
#' in \pkg{stringi}, refer to \code{\link{stri_opts_collator}}.
#' Please note that different locale settings may lead to different results
#' (see the examples below).
#'
#'
#' @param e1,e2 character vectors or objects coercible to character vectors
#' @param opts_collator a named list with \pkg{ICU} Collator's options
#' as generated with \code{\link{stri_opts_collator}}, \code{NULL}
#' for default collation options.
#' @param ... additional settings for \code{opts_collator}
#'
#' @return The \code{stri_cmp} and \code{stri_compare} functions
#' return an integer vector with comparison results of corresponding
#' pairs of elements in \code{e1} and \code{e2}:
#' \code{-1} if \code{e1[...] < e2[...]},
#' \code{0} if they are canonically equivalent, and \code{1} if greater.
#'
#' The other functions return a logical vector that indicates
#' whether a given relation holds between two corresponding elements
#' in \code{e1} and \code{e2}.
#'
#' @references
#' \emph{Collation} - ICU User Guide,
#' \url{http://userguide.icu-project.org/collation}
#'
#' @examples
#' # in Polish ch < h:
#' stri_cmp_lt("hladny", "chladny", locale="pl_PL")
#'
#' # in Slovak ch > h:
#' stri_cmp_lt("hladny", "chladny", locale="sk_SK")
#'
#' # < or > (depends on locale):
#' stri_cmp("hladny", "chladny")
#'
#' # ignore case differences:
#' stri_cmp_equiv("hladny", "HLADNY", strength=2)
#'
#' # also ignore diacritical differences:
#' stri_cmp_equiv("hladn\u00FD", "hladny", strength=1, locale="sk_SK")
#'
#' # non-Unicode-normalized vs normalized string:
#' stri_cmp_equiv(stri_trans_nfkd("\u0105"), "\u105")
#'
#' # note the difference:
#' stri_cmp_eq(stri_trans_nfkd("\u0105"), "\u105")
#'
#' # ligatures:
#' stri_cmp_equiv("\ufb00", "ff", strength=2)
#'
#' # phonebook collation
#' stri_cmp_equiv("G\u00e4rtner", "Gaertner", locale="de_DE@@collation=phonebook", strength=1L)
#' stri_cmp_equiv("G\u00e4rtner", "Gaertner", locale="de_DE", strength=1L)
#'
#' @family locale_sensitive
#' @export
#' @rdname stri_compare
stri_compare <- function(e1, e2, ..., opts_collator=NULL) {
   if (!missing(...))
       opts_collator <- do.call(stri_opts_collator, as.list(c(opts_collator, ...)))
   .Call(C_stri_cmp, e1, e2, opts_collator)
}


#' @export
#' @rdname stri_compare
stri_cmp <- stri_compare


#' @export
#' @rdname stri_compare
stri_cmp_eq <- function(e1, e2) {
   .Call(C_stri_cmp_eq, e1, e2)
}


#' @export
#' @rdname stri_compare
stri_cmp_neq <- function(e1, e2) {
   .Call(C_stri_cmp_neq, e1, e2)
}


#' @export
#' @rdname stri_compare
stri_cmp_equiv <- function(e1, e2, ..., opts_collator=NULL) {
   if (!missing(...))
       opts_collator <- do.call(stri_opts_collator, as.list(c(opts_collator, ...)))
   .Call(C_stri_cmp_equiv, e1, e2, opts_collator)
}


#' @export
#' @rdname stri_compare
stri_cmp_nequiv <- function(e1, e2, ..., opts_collator=NULL) {
   if (!missing(...))
       opts_collator <- do.call(stri_opts_collator, as.list(c(opts_collator, ...)))
   .Call(C_stri_cmp_nequiv, e1, e2, opts_collator)
}

#' @export
#' @rdname stri_compare
stri_cmp_lt <- function(e1, e2, ..., opts_collator=NULL) {
   if (!missing(...))
       opts_collator <- do.call(stri_opts_collator, as.list(c(opts_collator, ...)))
   .Call(C_stri_cmp_lt, e1, e2, opts_collator)
}


#' @export
#' @rdname stri_compare
stri_cmp_gt <- function(e1, e2, ..., opts_collator=NULL) {
   if (!missing(...))
       opts_collator <- do.call(stri_opts_collator, as.list(c(opts_collator, ...)))
   .Call(C_stri_cmp_gt, e1, e2, opts_collator)
}

#' @export
#' @rdname stri_compare
stri_cmp_le <- function(e1, e2, ..., opts_collator=NULL) {
   if (!missing(...))
       opts_collator <- do.call(stri_opts_collator, as.list(c(opts_collator, ...)))
   .Call(C_stri_cmp_le, e1, e2, opts_collator)
}


#' @export
#' @rdname stri_compare
stri_cmp_ge <- function(e1, e2, ..., opts_collator=NULL) {
   if (!missing(...))
       opts_collator <- do.call(stri_opts_collator, as.list(c(opts_collator, ...)))
   .Call(C_stri_cmp_ge, e1, e2, opts_collator)
}


#' @title
#' Compare Strings with or without Collation
#'
#' @description
#' Relational operators for comparing corresponding strings in
#' two character vectors, with a typical \R look-and-feel.
#'
#' @details
#' These functions call \code{\link{stri_cmp_le}} or its
#' friends, using default collator options.
#' Thus, they are vectorized over \code{e1} and \code{e2}.
#'
#' \code{\%stri==\%} tests for canonical equivalence of strings
#' (see \code{\link{stri_cmp_equiv}}) and is a locale-dependent operation.
#' On the other hand, \code{\%stri===\%} performs a locale-independent,
#' code point-based comparison.
#'
#'
#' @param e1,e2 character vectors or objects coercible to character vectors
#'
#' @return All the functions return a logical vector
#' indicating the result of a pairwise comparison.
#' As usual, the elements of shorter vectors are recycled if necessary.
#'
#'
#' @examples
#' "a" %stri<% "b"
#' c("a", "b", "c") %stri>=% "b"
#'
#' @usage
#' e1 \%s<\% e2
#'
#' @family locale_sensitive
#' @rdname oper_comparison
#' @export
"%s<%" <- function(e1, e2) {
   stri_cmp_lt(e1, e2)
}


#' @usage
#' e1 \%s<=\% e2
#' @rdname oper_comparison
#' @export
"%s<=%" <- function(e1, e2) {
   stri_cmp_le(e1, e2)
}


#' @usage
#' e1 \%s>\% e2
#' @rdname oper_comparison
#' @export
"%s>%" <- function(e1, e2) {
   stri_cmp_gt(e1, e2)
}


#' @usage
#' e1 \%s>=\% e2
#' @rdname oper_comparison
#' @export
"%s>=%" <- function(e1, e2) {
   stri_cmp_ge(e1, e2)
}


#' @usage
#' e1 \%s==\% e2
#' @rdname oper_comparison
#' @export
"%s==%" <- function(e1, e2) {
   stri_cmp_equiv(e1, e2)
}


#' @usage
#' e1 \%s!=\% e2
#' @rdname oper_comparison
#' @export
"%s!=%" <- function(e1, e2) {
   stri_cmp_nequiv(e1, e2)
}


#' @usage
#' e1 \%s===\% e2
#' @rdname oper_comparison
#' @export
"%s===%" <- function(e1, e2) {
   stri_cmp_eq(e1, e2)
}


#' @usage
#' e1 \%s!==\% e2
#' @rdname oper_comparison
#' @export
"%s!==%" <- function(e1, e2) {
   stri_cmp_neq(e1, e2)
}


#' @usage
#' e1 \%stri<\% e2
#' @rdname oper_comparison
#' @export
"%stri<%" <- function(e1, e2) {
   stri_cmp_lt(e1, e2)
}


#' @usage
#' e1 \%stri<=\% e2
#' @rdname oper_comparison
#' @export
"%stri<=%" <- function(e1, e2) {
   stri_cmp_le(e1, e2)
}


#' @usage
#' e1 \%stri>\% e2
#' @rdname oper_comparison
#' @export
"%stri>%" <- function(e1, e2) {
   stri_cmp_gt(e1, e2)
}


#' @usage
#' e1 \%stri>=\% e2
#' @rdname oper_comparison
#' @export
"%stri>=%" <- function(e1, e2) {
   stri_cmp_ge(e1, e2)
}


#' @usage
#' e1 \%stri==\% e2
#' @rdname oper_comparison
#' @export
"%stri==%" <- function(e1, e2) {
   stri_cmp_equiv(e1, e2)
}


#' @usage
#' e1 \%stri!=\% e2
#' @rdname oper_comparison
#' @export
"%stri!=%" <- function(e1, e2) {
   stri_cmp_nequiv(e1, e2)
}


#' @usage
#' e1 \%stri===\% e2
#' @rdname oper_comparison
#' @export
"%stri===%" <- function(e1, e2) {
   stri_cmp_eq(e1, e2)
}


#' @usage
#' e1 \%stri!==\% e2
#' @rdname oper_comparison
#' @export
"%stri!==%" <- function(e1, e2) {
   stri_cmp_neq(e1, e2)
}
